How about dropping the ziggurats making the main castle invulnerable but perhaps make smaller shield units (ziggurats or deamons or whatever) In return they can be a race focused on melee so they got the means to close in but that they have a severely reduced ranged arsenal (outside magic) However the shields should not really put much of a penality on melee combat, a walkthrough shield that could be great for the charge Just an idea Also the shield can have a certain amount of energy. It could be fun having a faction like that

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One day, someone showed me a glass of water that was half full. And he said, "Is it half full or half empty?" So I drank the water. No more problem. ~Alexander Jodorowsky